Magazine for semi-automatic and automatic firearm

ABSTRACT

A firearm magazine includes a magazine body, with the magazine body having a width to accommodate a double stack of cartridges in a zigzag pattern. The firearm magazine also includes a spring coupled to a follower within the magazine body. The firearm magazine body also includes two feed lips coupled to the magazine body, where the two feed lips together hold a single cartridge in place in a center of the magazine body to allow a bolt to push the single cartridge out of the firearm magazine and into a chamber of a firearm.

BACKGROUND Field

Embodiments of the present disclosure generally relate to firearm magazines. More specifically, the disclosure relates to an improved high capacity magazine design that allows for the feeding of ammunition without the use of feed ramps and/or allows an existing magazine to be used for larger cartridges than the magazine's original design.

Description of the Related Art

Magazines for automatic and semi-automatic firearms are often of the high capacity design to provide the firearm with a reasonable amount of ammunition. Magazines can be comprised of metal, various polymers, or any other suitable material, including a combination of materials. Magazines may be made as one piece of folded material or as multiple sections attached together.

To maximize the use of the space inside the magazine, and to keep the magazine as small as possible, the ammunition is often arranged in a “double stack” configuration to reach the high capacity desired. Double stack refers to the two vertical columns of cartridges arranged next to each other in a staggered zigzag pattern (See FIG. 1A) when the magazine is loaded. The magazines are also configured in a “double feed” configuration. That is, the double feed design has two feed lips—one on each side of the magazine which holds the top cartridge in each stack in place. Each feed lip retains one cartridge. FIG. 1A illustrates a magazine 100 utilizing a double stack/double feed configuration. The cartridges 114 are arranged inside the magazine body 102 as illustrated. These two columns of cartridges 114 extend from the top to the bottom of magazine 100 when magazine 100 is fully loaded.

Magazine 100 has a coil type spring 104 on the inside of magazine 100 that extends from the bottom of magazine 100 to the top. Floor plate 112 is at the bottom of magazine 100. On top of the spring 104 is a plastic or metal piece called a follower 106 formed to guide the cartridges 114 into place as the cartridges are loaded into magazine 100. As magazine 100 is loaded, spring 104 compresses until magazine 100 is fully loaded. The cartridges 114 are contained inside magazine 100 by feed lips 108 at the top of magazine 100. There are two feed lips 108 on a double stack/double feed configured magazine, one on each side of the magazine. Feed lips 108 are curved pieces of metal or plastic that are attached to and extend from the sides of magazine 100. Feed lips 108 are curved at a desired angle to maintain the top-positioned cartridge 114 in position in the magazine 100. As shown in FIG. 1A, each feed lip 108 retains one cartridge 114: the cartridge 114 that is on the side of the magazine that the respective feed lip 108 is on. In this example, the left feed lip 108 is retaining the topmost cartridge 114 in magazine 100. After the topmost cartridge 114 is removed from the magazine and chambered into the firearm, the next highest cartridge 114 at the top of the right side stack of cartridges 114 will move into the topmost position in the magazine 100 and will be held in position by the right feed lip 108.

Cartridges 114 are held up against the underside of feed lips 108 by the upward force exerted by magazine spring 104. There is a space (bolt channel 110) between the inside edges of the two feed lips 108 to allow the firearm's bolt to pass through as the bolt moves forward and pushes cartridges 114 out of magazine 100 and into the chamber of the firearm.

FIG. 1B illustrates a magazine 150 comprising a single stack/single feed configuration. Cartridges 114 are arranged in a single vertical stack within magazine body 102. Feed lips 108 both hold the topmost cartridge 114 at the top of magazine 150, with bolt channel 110 between feed lips 108. Follower 106, spring 104, and floor plate 112 operate similarly to the double stack/double feed magazine described above in FIG. 1A. A single stack/single feed magazine is generally thinner than a double stack/double feed magazine of similar length and caliber, but the single stack/single feed magazine holds fewer cartridges.

FIG. 2 illustrates a top view of double stack/double feed magazine 100. As shown, cartridges 114 are arranged in a staggered zigzag pattern within magazine body 102. Bolt channel 110 is shown between feed lips 108. During operation, cartridges 114 are removed or “stripped” from magazine 100 by the bolt of the firearm as the bolt cycles back and forth during firing, which removes the top cartridge 114 in magazine 100 each time the firearm fires. A cartridge 114 is removed from one side of magazine 100 and then the other side of magazine 100 in an alternating pattern until magazine 100 is empty. As shown in FIG. 2, the feed lip 108 on the left is holding the top cartridge 114 in place.

FIG. 3 illustrates an empty double stack/double feed magazine 100 containing no cartridges 114. Spring 104 is extended from the bottom of magazine 100 (near floor plate 112) to the top of magazine 100, where follower 106 is shown near feed lips 108 and bolt channel 110.

FIG. 4 illustrates top, side, and rear views of a double stack/double feed magazine 100, curved with stiffening grooves. As seen in the side view of magazine 100, the magazine is curved and includes a number of stiffening grooves 116. Feed lips 108 are also visible in the top, side, and rear views of magazine 100. Bolt channel 110 is shown in the rear and top view of magazine 100.

FIG. 5 illustrates top, side, and rear views of a double stack/double feed magazine 100, straight with stiffening grooves. As seen in the side view of magazine 100, the magazine is straight from top to bottom and includes a number of stiffening grooves 116. Feed lips 108 are also visible in the side and rear views of magazine 100. Bolt channel 110 is shown in the rear and top view of magazine 100.

FIG. 6 illustrates top, side, and rear views of a double stack/double feed magazine, curved without stiffening grooves. As seen in the side view of magazine 100, the magazine is curved. Feed lips 108 are also visible in the top, side, and rear views of magazine 100. Bolt channel 110 is shown in the rear and top view of magazine 100.

FIG. 7 illustrates top, side, and rear views of a double stack/double feed magazine, straight without stiffening grooves. As seen in the side view of magazine 100, the magazine is straight. Feed lips 108 are also visible in the side and rear views of magazine 100. Bolt channel 110 is shown in the rear and top view of magazine 100.

Conventional double stack/double feed magazines have several benefits, such as maximizing the space available to contain as many cartridges as possible while keeping the magazine as small as possible. However, there are also drawbacks to the conventional double stack design. As mentioned above, double stack configured magazines utilize a feed lip on each side of the magazine to contain and align the cartridges in a horizontal tip forward position.

The chamber of a firearm is located in the center of the barrel. A double stack/double feed configured magazine presents the cartridges in a low offset position as the cartridges relate to the chamber of the firearm, with each stack of cartridges off to a side of and just below the chamber, as illustrated in FIGS. 1A and 2. For the cartridges from the two columns in the magazine to enter the chamber correctly, the cartridges must be directed into the chamber from the cartridge's offset positions in the magazine.

FIG. 8 illustrates a front view of a barrel extension 200 with feed ramps 202. The cartridges in a double stack/double feed magazine are directed into the chamber of the firearm by feed ramps 202 located directly in front of the top cartridge on each side of the magazine. These feed ramps 202 are angled channels or ramps machined into the barrel extension 200 attached to the barrel of the firearm and are used to guide the cartridges into the chamber 204 as the cartridges are pushed forward and out of the magazine by the bolt. As the bolt cycles, the top cartridge located under the feed lip of the magazine is pushed forward by the bolt of the firearm, and the cartridge moves in a straight horizontal fashion until the projectile in the cartridge contacts the beveled feed ramp 202 on the barrel extension 200. As the cartridge continues to move forward the cartridge is deflected upward and inward towards the center line of the firearm and into the chamber 204 of the firearm.

When the cartridge is pushed forward by the bolt as the firearm cycles, it is moved with a great amount of force and velocity. When the projectile in the cartridge engages the steel feed ramp 202 with this force, the tip of the projectile can be dented or deformed which degrades the aerodynamic properties of the projectile thereby reducing accuracy of the projectile.

Additionally, hunters often use soft point ammunition with exposed soft lead tips that are required for hunting and that accelerate the expansion of the projectile. These exposed lead tips can be severely damaged by the feed ramps 202, degrading the accuracy of the hunting ammunition and resulting in wounded or wasted animals.

Another drawback to the use of feed ramps 202 in barrel extensions of semi-automatic and automatic firearms to deflect and direct the cartridges into the chamber 204 of the firearm is that each feed ramp 202 is located just below a bolt lug recess cut into the barrel extension. Bolt lug recesses 206 are illustrated in FIG. 8. The barrel extension 200 is a round metal collar screwed onto the back of the barrel that has teeth or “lugs” 212 that give the bolt of the firearm something to lock into to contain the high pressures of the cartridge when the cartridge is fired. Between each lug 212 of the barrel extension is a recess 206 or slot that allows passage of the lugs on the bolt to pass through as the bolt enters the extension 200 and locks thereinto.

The bolt lug recesses 206 have a square shape with sharp edges 208 on all three sides. As the cartridge is deflected into the chamber, the projectile impacts the feed ramps 202 and passes through the bolt lug recess 206. As the cartridge passes through, the projectile often comes into contact with the sharp edges 208 which can further damage the jacket of the projectile and further degrade the projectile's accuracy. The damage to the projectile by the barrel extensions' sharp lug recess edges 208 becomes more severe as the caliber of the projectile increases. Smaller caliber projectiles that are close to the width of the recess 206 may pass through with little or no damage, but larger caliber projectiles can receive major damage as the large projectile attempts to pass through the narrow recess 206. Feeding of large projectiles can even cause enough of a drag as the projectile's jacket digs into the sharp edges of the recess 206 to slow down the bolt of the firearm and cause the firearm to malfunction.

Military and law enforcement snipers as well as civilian competition shooters often prefer semiautomatic rifles and use match ammunition loaded with match grade projectiles that deliver excellent accuracy at extreme distances. Match grade projectiles are manufactured to exacting tolerances for consistency, including almost identical weights, jacket thickness concentricity, aerodynamic profiles, and perfectly formed tips. When these match grade projectiles engage the steel feed ramps 202 and sharp edges 208 of the bolt lug recesses 206, the match grade projectiles are often deformed which is detrimental to the precision design of the match grade projectiles and defeats the intended purpose of the match grade projectiles for improved long range accuracy. Degraded accuracy of match ammunition used by military and law enforcement snipers could mean the difference between life and death for a hostage or bystanders.

The most common semiautomatic firearm in use today by the military, law enforcement and civilian shooters is the AR15 (or AR10) style rifle. One of the reasons for the popularity of the AR15 style rifle is the modular two piece design of the AR15 style rifle which allows the upper and lower receivers to be exchanged with alternative upper or lower receivers. This modular design allows the owner of one lower receiver to have multiple upper receivers, and therefore multiple calibers for one firearm. The lower receiver contains the magazine well, which is the recess where the magazine is inserted into the firearm. The magazine well is a fixed size and only accepts one size of magazine.

While the upper receiver of the firearm can be replaced easily to change from one caliber or cartridge to another, altering the magazine to accept additional cartridges is not as easy. The double stack/double feed design magazines for AR15 type (or AR10) rifles have been slightly modified successfully to accept several slightly larger cartridges, but the double stack design magazine also has limitations to the size of cartridges the double stack magazine can accept. The two major limiting factors are feed lip adaptability and stack geometry.

As discussed above, feed lips 108 are metal flaps attached to the sidewall of the magazine 100 that are bent over the top of the magazine 100 to contain the cartridges 114 inside the magazine 100 and to help guide the cartridges 114 into the chamber 204. Feed lips 108 are curved at an angle to retain the cartridge case, for which the magazine was designed, in the magazine. There is also a minimum amount of space required between the feed lips 108 for the bolt of the firearm to pass through (i.e., the bolt channel 110) as it pushes the cartridges 114 out of the magazine 100 and into the chamber 204 (see, e.g., FIGS. 1A, 2, and 8). As the cartridge case gets larger in diameter, the width of each feed lip 108 must also be increased to securely hold the larger case in place. As the width of the feed lips 108 is increased, the width between the two feed lips 108 is reduced. The width between the two feed lips 108 determines the “bolt channel” 110, which is required for the firearm to operate, and thus limits the diameter of the cartridge case the double stack/double feed magazine 100 can adapt to.

FIG. 9 illustrates a sectioned side view of a barrel extension 200. Barrel extension lugs 212 are visible, and the bolt lug recesses 206 are not visible but are illustrated by a dotted line. Chamber 204 is shown in barrel 210. Feed ramps 202 are also illustrated.

As the cartridge case becomes larger in diameter, the tip of the projectile is located in a lower position as it relates to the feed ramp 202 when compared to a smaller diameter cartridge case because the feed lips 108 are in a fixed location and cannot be moved. For example, a cartridge position 220 for a double feed magazine is illustrated with an arrow in FIG. 9. When the tip of the projectile is located in this lower position 220, the projectile may miss the leading edge of the feed ramp 202 and stop moving forward when the projectile hits the flat inside surface of the barrel extension 200 or upper receiver, thereby causing a feed jam and causing the firearm to malfunction.

Stack geometry refers to the way the cartridges 114 position themselves and move inside the magazine 100 when the magazine is loaded. Magazines are originally designed and built for a specific cartridge. A traditional double stack type of magazine has a width to accommodate two vertical columns of selected cartridges side by side in a zigzag pattern from top to bottom, as illustrated in FIG. 1A. With “good stack geometry,” the entire stack of cartridges moves freely up and down inside the magazine with virtually no outward forces or resistance in the magazine. As such, the cartridges will “feed” correctly into the firearm and the magazine will be reliable. The right side of FIG. 19 illustrates a double stack magazine where the forces, such as force 510, are generally vertical within the magazine 502, which allows the cartridges 114 to move up and down inside the magazine and feed correctly.

The width of the cartridge stack in a traditional double stack magazine is approximately 188% of the width of the cartridge case, measured at the rear of the case. In this configuration, each cartridge in the stack, except for the top and bottom cartridges, is touching at least two other cartridges in the stack. Some of the cartridges may touch three or four other cartridges in the stack.

As mentioned above, the magazine has a predetermined physical size to which the magazine is limited to accommodate the magazine well of the firearm. When attempting to modify the magazine to accept larger diameter cases, the “stack geometry” inside the magazine changes. The internal dimensions of the magazine cannot be made larger or modified much because the double feed configuration requires a cartridge under each feed lip 108 on each side of the magazine. As the cartridge cases get larger in diameter the cartridge cases will have larger spaces therebetween when the magazine is loaded, which creates an outward force on the sides of the magazine. The left side of FIG. 19 illustrates the forces 512 that can create an outward force on the sides of the magazine when the magazine is loaded with larger cartridges, or when the width of the magazine is narrower than a conventional double stack magazine.

When this happens, the cartridges in the magazine do not move up and down freely inside the magazine and can actually cause a bulge in the outer walls of the magazine. This can cause the cartridges to jam together inside the magazine, causing a feed jam and the firearm to malfunction. This bulging of the magazines side walls also makes it difficult to insert and release the magazine from the firearm. Double stack/double feed types of magazines can therefore be modified to accept cartridges larger than originally designed, but only minimally.

When attempting to narrow the width of the double stack of cartridges there is a width or range that alters the up and down forces of the double stack of cartridges and redirects the forces on the cartridges to the outside walls of the magazine (see, e.g., FIG. 19).

This “failure or wedge zone” where the cartridges exert forces to the outside walls of the magazine is from approximately 150% to 180% percent of the width of the cartridge case. Previous attempts to adapt larger cartridges to existing magazines have resulted in failure because they have attempted to adapt the cartridges to a stack width that falls in this failure zone.

What is needed is an improved magazine design for semiautomatic and automatic rifles, as well as a design that can be adapted for bolt action rifles.

SUMMARY

The present disclosure generally relates to firearm magazines for automatic and semi-automatic firearms, and more particularly to a design that allows for the advantages of a double stack magazine for high capacity while utilizing a single feed style mechanism for positioning and guiding the cartridges into the chamber. An improved magazine design allows for the use of larger diameter cartridges other than what the magazine was originally designed for, allowing larger diameter cartridges for use in smaller firearms. In military applications, larger diameter cartridges may be more effective against armor used by opposing forces. Embodiments described herein allow an existing lower receiver to shoot larger diameter cartridges without requiring the purchase of a new weapon. An improved magazine design also utilizes a single feed design, allowing the internal width of the magazine to be adjusted to provide a good stack geometry without affecting the feeding of the cartridges from the magazine.

In one aspect, a firearm magazine includes a magazine body, with the magazine body having a width to accommodate a double stack of cartridges in a zigzag pattern. The firearm magazine also includes a spring coupled to a follower within the magazine body. The firearm magazine body also includes two feed lips coupled to the magazine body, where the two feed lips together hold a single cartridge in place in a center position of the magazine body to allow a bolt to push the single cartridge out of the firearm magazine and into a chamber of a firearm.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.

FIG. 1A illustrates a rear view of a loaded double stack/double feed configured magazine;

FIG. 1B illustrates a rear view of a loaded single stack/single feed configured magazine;

FIG. 2 illustrates a top view of a loaded double stack/double feed configured magazine;

FIG. 3 illustrates a rear view of an unloaded double stack/double feed configured magazine;

FIG. 4 illustrates top, side, and rear views of a double stack/double feed magazine, curved with stiffening grooves;

FIG. 5 illustrates top, side, and rear views of a double stack/double feed magazine, straight with stiffening grooves;

FIG. 6 illustrates top, side, and rear views of a double stack/double feed magazine, curved without stiffening grooves;

FIG. 7 illustrates top, side, and rear views of a double stack/double feed magazine, straight without stiffening grooves;

FIG. 8 illustrates a front view of a barrel extension with feed ramps;

FIG. 9 illustrates a sectioned side view of a barrel extension;

FIG. 10 illustrates a top view of a loaded double stack/single feed configured magazine, according to an embodiment;

FIG. 11 illustrates a rear view of an unloaded double stack/single feed configured magazine, according to an embodiment;

FIG. 12A illustrates a rear view of a loaded double stack/single feed configured magazine, according to an embodiment;

FIG. 12B illustrates a rear view of a loaded double stack/single feed configured magazine, according to another embodiment;

FIG. 13 illustrates top, side, and rear views of a double stack/single feed magazine, curved with stiffening grooves, according to an embodiment;

FIG. 14 illustrates top, side, and rear views of a double stack/single feed magazine, straight with stiffening grooves, according to an embodiment;

FIG. 15 illustrates top, side, and rear views of a double stack/single feed magazine, curved without stiffening grooves, according to an embodiment;

FIG. 16 illustrates top, side, and rear views of a double stack/single feed magazine, straight without stiffening grooves, according to an embodiment;

FIG. 17 illustrates a magazine including a narrow double stack section and a wide double stack section, according to another embodiment;

FIG. 18 illustrates cartridge path locations on a sectioned side view of a barrel extension; and

FIG. 19 illustrates “failure zone” forces on cartridges and magazine bodies in a narrow double stack cartridge configuration and a wide double stack cartridge configuration.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

The present disclosure generally relates to firearm magazines, and more specifically to a design that allows for the advantages of a double stack magazine for high capacity while utilizing a single feed style mechanism for positioning and guiding the cartridges into the chamber.

Embodiments described herein maintain the double stack configuration for the loaded cartridges but utilize a single feed design instead of the traditional double feed design. As mentioned previously, the double feed design has two feed lips—one on each side of the magazine which holds the top cartridge in each stack in place. Therefore each feed lip retains one cartridge (i.e., the top cartridge is retained by one feed lip). The double stack/single feed design has one set of feed lips that position one cartridge in the center top of the magazine. Therefore, both feed lips retain a single cartridge in the center position. The feed lips of the single feed design are curved to direct the cartridges into the single feed position but do not need to be shaped to match the curvature of the cartridge case. Instead, the feed lips are angled inward from each side of the magazine at an angle that best guides the cartridges, depending on diameter, from each stack into the center of the magazine and into the single feed position.

Embodiments described herein may utilize a narrow double stack cartridge configuration or a wide double stack cartridge configuration. In the narrow double stack cartridge configuration, each cartridge in the fully or almost fully loaded magazine touches two other cartridges, except for the top and bottom cartridges, which only contact one other cartridge (see, e.g., FIG. 12A).

In the wide double stack cartridge configuration, each cartridge in the fully or almost fully loaded magazine touches three or four other cartridges, except for the top and bottom cartridges, which may only touch one or two other cartridges (see e.g., FIG. 12B).

In another embodiment, a magazine body may comprise a first section with a first width where the cartridges are arranged in a narrow double stack cartridge configuration, and may also comprise a second section with a second width where the cartridges are arranged in a wide double stack cartridge configuration, as discussed with respect to FIG. 17 below.

FIG. 10 illustrates a top view of a loaded double stack/single feed configured magazine, according to one embodiment described herein. Magazine 300 comprises a magazine body 302 and feed lips 308. As shown, cartridge 114 is centered in the magazine 300 when it is at the top of the magazine 300 and is the next cartridge to be fed into the chamber of the firearm.

The double stack magazine 300 with a single feed design utilizes a similar internal design to store the cartridges as the double stack/double feed high capacity magazine described above in FIGS. 1A and 2-7. The double stack/single feed magazine 300 has two vertical columns of cartridges located next to each other arranged in a zigzag type configuration. The single feed magazine design also utilizes a similar coil type magazine spring on the inside that extends from the top of the magazine to the bottom, and which utilizes a follower on the top of the spring to guide the cartridges as they are loaded into the magazine.

FIG. 11 illustrates a rear view of an unloaded double stack/single feed configured magazine 300, according to an embodiment. The inside of magazine body 302 contains a follower 306 coupled to magazine spring 304. The magazine spring 304 extends from floor plate 312 to the top of magazine 300, and is compressed when cartridges are loaded into the magazine 300. Feed lips 308 and bolt channel 310 are also illustrated in FIG. 11.

FIG. 12A illustrates a rear view of a loaded double stack/single feed configured magazine 300 with a narrow double stack, according to an embodiment. Cartridges are loaded within magazine body 302. Spring 304 is compressed and extends from floor plate 312 to follower 306, which is in contact with the bottom-most cartridge 114 in magazine 300. Feed lips 308 are configured to center the top cartridge 114 into bolt channel 310 so that the top cartridge can be fed into the chamber.

In the narrow double stack cartridge configuration, each cartridge in the fully or almost fully loaded magazine touches two other cartridges, except for the top and bottom cartridges, which only contact one other cartridge. In the narrow double stack cartridge configuration, the width of the cartridge stack is approximately less than 150% of the width of the cartridge case. Thus, the width of the cartridge stack is outside of the failure zone as described above.

FIG. 12B illustrates a rear view of a loaded double stack/single feed configured magazine 350 with a wide double stack, according to an embodiment. Cartridges 114 are loaded within magazine body 352. As shown, spring 354 is compressed and extends from floor plate 362 to follower 356, which is in contact with the bottom-most cartridge 114 in magazine 350. Feed lips 358 are configured to center the top cartridge 114 into bolt channel 360 so that the top cartridge can be fed into the chamber.

In the wide double stack cartridge configuration, each cartridge in the fully or almost fully loaded magazine touches three or four other cartridges, except for the top and bottom cartridges, which may only touch one or two other cartridges. In the wide double stack cartridge configuration, the width of the cartridge stack is approximately greater than 180% of the width of the cartridge case. Thus, the width of the cartridge stack is outside of the failure zone as described above.

Although the double stack/single feed magazine design illustrated in FIGS. 12A and 12B maintains the double stack configuration, the single centered feed lip location allows the width of the double stack of cartridges to be altered to maximize the stack geometry without affecting the functioning of the magazine.

The single feed design also requires less force from the bolt as the firearm cycles because the cartridge is easily fed from the magazine and into the chamber with less resistance. The double feed design, in contrast, requires more force from the bolt to overcome the resistance created when the cartridges engage the feed ramps and are redirected into the chamber. As the projectile in the cartridge engages the feed ramp as the cartridge moves forward, the rear half of the cartridge case is still under the feed lip. As the front of the cartridge is deflected up due to the contact with the feed ramp, the rear of the cartridge is deflected down and must push the remaining cartridges in the magazine down and compress the magazine spring until the rear of the cartridge is pushed out from under the feed lip. This movement also causes resistance on the bolt as the cartridge is fed from the magazine.

The double stack/single feed magazine functions in much the same manner as a traditional double stack/double feed magazine in that the cartridges are removed or “stripped” from the magazine by the bolt as the firearm cycles. Both designs utilize a magazine spring that pushes the cartridges up from the bottom of the magazine and “feeds” them as the firearm cycles, while the cartridges are retained in the magazine by the feed lips at the top of the magazine.

The double stack/single feed design, however, allows the magazine feed lips to present the cartridge in a centered and more elevated position when compared to a traditional double stack/double feed design. A comparison of FIGS. 1A and 12B illustrates the difference of the position of the top cartridge in the magazine between the double feed design (FIG. 1A) and the single feed design (FIG. 12B). The elevated and centered location in the single feed design positions the cartridge more in line with the chamber of the firearm and allows the cartridge to be stripped or fed from the magazine by the bolt and directly into the chamber with less opportunity for the projectile to contact any feed ramps or bolt lug recesses or any other parts of the firearm.

Cartridges fed from a magazine with a single feed design will generally be more accurate than those from a traditional double feed design because the projectiles will not be damaged as the cartridges are fed from the magazine and into the chamber.

FIG. 13 illustrates top, side, and rear views of a double stack/single feed magazine 300, curved with stiffening grooves, according to an embodiment. As seen in the side view of magazine 300, the magazine is curved and includes a number of stiffening grooves 316. Feed lips 308 are also visible in the top, side, and rear views of magazine 300. Bolt channel 310 is shown in the rear view of magazine 300.

FIG. 14 illustrates top, side, and rear views of a double stack/single feed magazine 300, straight with stiffening grooves, according to an embodiment. As seen in the side view of magazine 300, the magazine is straight from top to bottom and includes a number of stiffening grooves 316. Feed lips 308 are also visible in the side and rear views of magazine 300. Bolt channel 310 is shown in the rear view of magazine 300.

FIG. 15 illustrates top, side, and rear views of a double stack/single feed magazine 300, curved without stiffening grooves, according to an embodiment. As seen in the side view of magazine 300, the magazine is curved. Feed lips 308 are also visible in the side and rear views of magazine 300. Bolt channel 310 is shown in the rear view of magazine 300.

FIG. 16 illustrates top, side, and rear views of a double stack/single feed magazine 300, straight without stiffening grooves, according to an embodiment. As seen in the side view of magazine 300, the magazine is straight from top to bottom. Feed lips 308 are also visible in the side, top, and rear views of magazine 300. Bolt channel 310 is shown in the rear and top view of magazine 300.

FIG. 17 illustrates an example of a double stack/single feed magazine, according to another embodiment. Magazine 400 comprises feed lips 408 atop a magazine body 402. Floor plate 412, spring 404, and follower 406 are also illustrated. In this example embodiment, magazine body 402 is larger at the bottom of the magazine then at the top. Therefore the stack geometry of the cartridges in the magazine 400 will comprise cartridges in a wide or standard double stack pattern at the bottom of the magazine 400 and cartridges in a narrow double stack pattern at the top of the magazine 400. In one embodiment, the bottom portion of the magazine 400 is approximately 20% wider than the top portion of the magazine 400. In another embodiment, the bottom portion of magazine 400 is greater than 20% wider than the top portion of the magazine 400.

The structure of magazine 400 allows the narrower top portion of the magazine to fit into an existing smaller magazine well of a firearm, while the wider bottom portion allows for more rounds to fit into the magazine.

FIG. 18 illustrates cartridge path locations on a sectioned side view of a barrel extension. Chamber 204 is shown in barrel 210. Feed ramps 202 are also illustrated. As described with respect to FIG. 9 above, a cartridge position 220 for a double feed magazine is illustrated with an arrow. Also illustrated in FIG. 18 with an arrow is a cartridge position 230 for a single feed magazine. In a double feed magazine, the tip of the projectile is located in the lower position 220. In this lower position 220, the projectile may miss the leading edge of the feed ramp 202 and stop moving forward when the projectile hits the flat inside surface of the barrel extension 200 or upper receiver, thereby causing a feed jam and causing the firearm to malfunction. However, with a single feed magazine according to the embodiments herein, the tip of the projectile is located in the upper position 230. In this position, the cartridge will not hit the flat surface of the barrel extension 200 and then stop moving forward. Instead, the cartridge is more likely to clear the barrel extension 200 and be loaded into the chamber 204 of the firearm without being obstructed or damaged. Therefore the double stack/single feed magazine as described herein provides an advantage over the conventional double stack/double feed magazine.

To disassemble one embodiment of the double stack/single feed magazine as described herein, the floor plate is removed by sliding the floor plate to the front or rear and off of the bottom of the magazine. Then, the coil spring and follower are removed by pulling them out the bottom of the magazine. Assembly of the magazine is in reverse order of disassembly.

Due to the single feed position in the center of the magazine having a bolt channel narrower than the cartridge case, loading of the cartridges must occur one at a time with the cartridges pushed into position from the front, which depresses the follower and slides the cartridge down and under the feed lips. Additional cartridges are fed the same way by depressing the cartridge that is already in the magazine down and sliding the next cartridge into the magazine on top of the one already in the magazine. The magazine is unloaded by sliding the cartridges out from under the feed lips from back to front one at a time until the magazine is empty.

FIG. 19 illustrates the forces in a wide double stack magazine and a narrow double stack magazine. In the wide double stack magazine, body 502 is shown containing cartridges 114. The forces 510 in the wide double stack magazine are generally straight up and down, and do not push against the sides of the magazine body.

FIG. 19 also illustrates the forces in a narrow double stack magazine. Body 504 contains cartridges 114, and forces 512 push outward against the body 504. The forces 512 can wedge the cartridges 114 in place, depending on the magnitude and the angle of the force 512. These forces 512 can cause the magazine to fail if the magazine is not constructed to the proper width. As described above, the “failure or wedge zone” where the cartridges exert forces to the outside walls of the magazine is approximately 150% to 180% of the width of the cartridge case. Previous attempts to adapt larger cartridges to existing magazines have resulted in failure because they have attempted to adapt the cartridges to a stack width that falls in this failure zone.

The double stack/single feed magazine has a number of advantages over conventional magazines. First, the double stack/single feed magazine maintains the high capacity design of conventional magazines. Second, the double stack/single feed magazine does not damage projectiles as much as the conventional design. Finally, the double stack/single feed magazine is easily adaptable for use with larger diameter cartridges.

Some embodiments herein use semiautomatic and automatic firearms as examples, particularly semiautomatic and automatic rifles that utilize barrel extensions. Embodiments described herein may also be utilized in bolt action rifles that utilize feed ramps with appropriate modifications, if necessary. Embodiments herein may utilize any magazine capacity, from one round to forty rounds or even higher.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1. A firearm magazine, comprising: a magazine body, the magazine body having a width to accommodate a double stack of cartridges in a zigzag pattern; a spring coupled to a follower within the magazine body; and two feed lips coupled to the magazine body, wherein the two feed lips together hold a single cartridge in place in a center of the magazine body to allow a bolt to push the single cartridge out of the firearm magazine and into a chamber of a firearm, wherein the width of the double stack of cartridges comprises less than 150% of a width of the single cartridge.
 2. The firearm magazine of claim 1, wherein every cartridge in the magazine body, except for the single cartridge held by the two feed lips, is configured in a double stack zigzag pattern within the magazine body.
 3. The firearm magazine of claim 1, wherein the magazine body has a straight profile.
 4. The firearm magazine of claim 1, wherein the magazine body has a curved profile.
 5. The firearm magazine of claim 1, wherein the magazine body increases in width over its length.
 6. The firearm magazine of claim 1, wherein the magazine body is comprised of metal.
 7. The firearm magazine of claim 1, wherein the magazine body is comprised of polymer.
 8. The firearm magazine of claim 1, the magazine having a constant width along a length thereof.
 9. The firearm magazine of claim 1, wherein the magazine body has a top portion with a first width to accommodate a narrow double stack of cartridges in a first zigzag pattern, and wherein the magazine body has a bottom portion with a second width greater than the first width, wherein the second width accommodates a wide double stack of cartridges in a second zigzag pattern.
 10. The firearm magazine of claim 1, wherein each cartridge in the firearm magazine touches two other cartridges, except for a top and a bottom cartridge, which each only touch one other cartridge.
 11. (canceled)
 12. A firearm magazine, comprising: a magazine body, wherein the magazine body has a top portion with a first width to accommodate a narrow double stack of cartridges in a first zigzag pattern, wherein the first width is less than 150% of a width of the single cartridge, and wherein the magazine body has a bottom portion with a second width greater than the first width, wherein the second width accommodates a wide double stack of cartridges in a second zigzag pattern; a spring coupled to a follower within the magazine body; and two feed lips coupled to the magazine body, wherein the two feed lips together hold a single cartridge in place in a center of the magazine body to allow a bolt to push the single cartridge out of the firearm magazine and into a chamber of a firearm.
 13. (canceled)
 14. The firearm magazine of claim 12, wherein the second width is greater than 180% of a width of the single cartridge.
 15. The firearm magazine of claim 12, wherein each cartridge in the top portion of the firearm magazine touches two other cartridges, except for a top cartridge, which only touches one other cartridge.
 16. The firearm magazine of claim 12, wherein each cartridge in the bottom portion of the firearm magazine touches two, three, or four other cartridges, except for a bottom cartridge which only touches one other cartridge.
 17. The firearm magazine of claim 12, wherein the magazine body has a straight profile.
 18. The firearm magazine of claim 12, wherein the magazine body has a curved profile.
 19. The firearm magazine of claim 12, wherein the magazine body is comprised of metal.
 20. The firearm magazine of claim 12, wherein the magazine body is comprised of polymer.
 21. A firearm magazine, comprising: a magazine body, the magazine body having a width to accommodate a double stack of cartridges in a zigzag pattern; a spring coupled to a follower within the magazine body; and two feed lips coupled to the magazine body, wherein the two feed lips together hold a single cartridge in place in a center of the magazine body to allow a bolt to push the single cartridge out of the firearm magazine and into a chamber of a firearm, wherein the width of the double stack of cartridges comprises less than 150% of a width of the single cartridge, wherein every cartridge in the magazine body, except for the single cartridge held by the two feed lips, is configured in the zigzag pattern and contained within the magazine body, and wherein the magazine body has a straight profile or a curved profile.
 22. The firearm magazine of claim 21, wherein each cartridge in the firearm magazine touches two other cartridges, except for a top and a bottom cartridge, which each only touch one other cartridge. 